GB2484912A

GB2484912A - Composite yarn formed from fabric selvedge with carbon-fibre tows

Info

Publication number: GB2484912A
Application number: GB1017902.6A
Authority: GB
Inventors: Mahmudul Hossain Akonda
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-10-25
Filing date: 2010-10-25
Publication date: 2012-05-02
Also published as: GB201017902D0

Abstract

The generally waste selvedge off-cut from a woven fabric can be recycled by forming a composite yarn comprising the catch-cord selvedge of a fabric which includes carbon fibre tows. The tows are short in length, preferably 5 to 200 mm. The yarn may be formed by spinning in a method comprising the steps of: (a) providing a catch-cord fabric selvedge comprising short carbon filament tows; (b) re-forming the catch-cord selvedge for positioning the tows in one direction; and (c) spinning the aligned tows so as to form a continuous yarn The tows are preferably not broken or disintegrated. The spinning may involve hollow spindle spinning, wrap spinning and thermal bonding and may incorporate heating or stretching. The wrapping material may comprise polymer filaments, ribbons or adhesive. The yarn is particularly suitable as reinforcing yarns in a thermoset composite.

Description

COMPOSITE YARN AND METHOD FOR THE PRODUCTION THEREOF FROM CATCH-CORD

FABRIC SELVEDGE

FIELD OF THE INVENTION

[00011 This invention concerns a novel approach to the production of composite yarn from catch-cord fabric selvedge of carbon fibre tows without breaking the tows or separating the filaments from the tows.

BACKGROUND TO THE INVENTION

100021 Carbon fibre has found widespread use in a variety of different applications due to its light weight and exceptional strength. This fibre also has the advantage of considerably lower density and this makes it an deal reinforcing fibre for applications requiring low weight. As a consequence of its advantageous properties, there has been a rapid growth in worldwide demand for the use of these fibres in composite materials. However, the uses of carbon fibres are mainly in tow form, where, untwisted continuous filaments stay together as a bundle to be used in woven fabric for composite applications.

[0003] The woven fabric of carbon fibres consists of two sets of tows; warp and weft, where the warp set runs along the fabric length and designates as 0 degrees whilst the weft sets run perpendicular to the warp tows. The weft tows are designated as 90 degrees and interwoven with the warp tows.

During the picking motion (weft tows insertion), the both ends of the inserted weft tows are cut by a cutting device and cut ends are left hanging out of the selvedge portion of the woven cloth. Such hanging weft ends may create faulty pick during subsequent weft insertion or damage the fabric selvedge. Therefore, to overcome this problem, an additional selvedge alongside the main fabric selvedge is produced by using catch-cord (binding yarn) for grasping and holding the severed ends of the inserted weft tows. During the fabric production, the additional selvedge with catch-cord is separated from the main fabric selvedge and the catch -cord selvedge is pulled or drawn off the loom.

[0004] The off-cut additional selvedge edge from both sides of the fabric with catch-cord is known as catch-cord selvedge or selvedge edge with catch-cord or selvedge waste, where the weft tows (weft picks of the fabric) are hold by binding threads (catch-cord). However, a significant amount of this selvedge waste containing short virgin carbon fibres tows (5 mm to 200 mm), generates in every single loom during the fabric production.

[00051 The catch-cord selvedge or selvedge edges after cutting from main fabric, become useless as there are no suitable methods have been developed yet to re-use them. However, the length of the tows in selvedge edge can be from 5 mm to 200 mm and the length of the catch-cord selvedge may be from 10 meter to 1000 meter or more as same as the fabric's length.

[0006] Recently, some methods have been developed for recovering the filaments from the catch-cord selvedge tows by using "fluidized bed" pyrolysis process in which the catch-cord selvedges/ off cut fabric selvedge are fed into fluidised gas chamber at 550°C to separate the individual filaments but the recovered fibres lose their physical strength significantly. Moreover, once the carbon fibres are separated from the tows, are very difficult to handle as they break easily under lower stress.

[0007] The other methods for re-using the short tows into composite, require series of mechanical actions for separating the filaments and blending with other fibres to make nonwoven veil or fibrous materials. But in those processes, the carbon fibre breaks into parts by mechanical actions involved as the fibres are very brittle in nature. Moreover, these processes are not suitable to produce yarn.

[0008] In addition, there are some references in the prior art (US patent 4856147) to the production of carbon fibre yarns using discontinuous carbon fibres filaments. In most of the processes employed for the production of the yarns, continuous carbon filaments are stretched and broken into discontinuous form. This method also requires the separation of individual carbon filaments to be commingled with polymer filaments. It is found, therefore, shorter and discontinuous carbon fiber tows cannot be processed to make yarn using stretch-broken commingling process.

[0009] Also, in the prior art, there are some methods disclosed by a Japanese Unexamined Patent Publications No. 6-100246 and by US Patent 2002/0157765 Al for splicing the longer fibre tows/bundles by injecting air. However, those disclosed methods are related to the joining of the two ends of the continuous tows not for the shorter tows.

[0010] Thus, surprisingly, no methods have been reported in the prior art which facilitate the production of yarns by direct using of the catch-cord selvedge or waste selvedge edge containing shorter carbon fibre tows. Moreover, there are no methods have been developed yet to use the short and off cut selvedge tows in a yarn avoiding any filaments breaking and filaments separating from the tows.

[0011] The present inventor, therefore, has examined the possibility for converting the catch-cord fabric selvedge or selvedge edge into yarn without disintegrating the tows or separating the tows from catch-cord. Such an approach would provide the technique to use the catch-cord selvedge directly into the yarn for composite applications.

SUMMARY OF INVENTION

[00121 The present discloser is directed to a novel method to make yarn by using the catch-cord fabric selvedge or off-cut fabric selvedge containing short carbon fiber tows without separating any tows from catch-cord selvedge and also without separating any filaments from the tows. According to a first aspect of the present invention there is provided a composite yarn comprising short carbon fibre tows.

[0013] In the context of the present invention, short carbon fibres tows are understood to be carbon fibre tows which typically have a length of from 5 mm to 200 mm. The composite yarn is obtained from short tows which preferably comprise a selvedge edge / catch-cord selvedge of woven fabric or re-formed catch-cord selvedge of carbon fabrics.

[0014] According to a second aspect of the present invention, there is provided a method for the production of a composite yarn from selvedge waste, said method comprising the steps of: (a) Catch-cord selvedge or selvedge edge or waste woven fabric selvedge containing short carbon fibre tows (b) Re-forming the selvedge edges as mentioned in (a) (c) Orientation of the short tows without breaking the tows or filaments (d) Compacting the oriented the tows (e) Formation of a yarn [0015] Typically, said, catch-cord selvedge or off-cut selvedge or selvedge waste which means that the part of the selvedge, which is separated from the main fabrics during weaving that holds the short carbon fibre tows. The one end of the tows is grasped by sewing/stitching thread or catch-cord and typically said the tows have count of from 1K to 30K.

[0016] Typically, said re-forming of the selvedge edge is achieved by means of techniques such as further trimming of stitching threads or modifying the selvedge stitch during weaving or after weaving to achieve required suitability of processed materials to convert into yarn.

[0017] Typically, said re-forming is achieved by means of techniques such as reducing or removing of the selvedge treads or catch-cord by using any suitable techniques such as burning or dissolution methods.

[0018] In one embodiment, re-forming can be achieved by adding any suitable thread or flexible tape or expandable materials with required properties such as flexibility, elasticity, low melting, self-adhesive along the cutting edge. For an example, elastic thread will be extended during stretching to create more space between the tows for better orientation of the tows during yarn formation.

[00191 In embodiments of the invention, catch-cord selvedge can be prepared during the weaving process in the loom to convert into yarn. Typically, said using modified cutting device, or adding suitable elastic threads or adhesive tape instead of conventional binding threads to hold the short tows to achieve required suitability of the selvedge trim for the next process.

[0020] In one embodiment, any suitable polymers, powders, solvents or liquids can be added along the trimming line of the additional selvedge during weaving or during re-forming.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments of the invention are further described hereinafter with references to the accompanying drawings, in which: Figure 1 is an illustration of a typical catch-cord woven fabric selvedge edge comprising short weft tows (weft picks in weaving) with binding (catch-cord) threads, which will be processed according to the method of the invention; Figure 2 shows a typical trimming process or re-forming process of the selvedge edge with or without adding of any suitable carriers to carry the short weft tows according to the method of invention; Figure 3 is an illustration of typical technique for orienting and condensing the tows in a unidirectional way by pulling the binding threads according to the method of the invention; Figure 4 depicts the a typical technique for aligning of the selvedge tows by stretching of the binding cord or threads according to the method of the invention; Figure 5 is an illustration of typical techniques for aligning of the tows by softening and stretching the binding threads under tension according to the method of the invention; Figure 6 depicts the a typical spinning device for converting the catch -cord woven selvedge into a twist less yarn and a typical yarn structure according to the method of the second aspect of the invention; and Figure 7 shows an illustration of typical techniques to make yarn from catch-cord selvedge by using fibrous tape according to the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention provides a novel composite yarn comprising catch-cord fabric selvedge which comprise short carbon fibre tows, and also provides a method for the production of said composite yarns.

[0023] According to this invention, techniques are provided in Figures 1 to 7 to convert the catch-cord fabric selvedge of carbon fibre tows into a yarn without breaking the tows and separating the carbon filaments from the tows.

[0024] According to the method of the invention, the catch-cord selvedges comprising said short carbon fiber tows are re-formed prior to passing through a spinning device to convert into yarn. The re-forming process may be performed by means of techniques such as further trimming or adding any suitable filaments for spinning operations.

[0025] Suitable procedures for the formation of a fabric selvedge based yarn include the re-forming of the catch-cord selvedge during weaving process, whereby the edge of the fabric selvedge can be prepared for spinning by trimming or adding any suitable filaments/threads/tape during cutting of the fabric selvedge in the loom or after loom.

[0026] In the case of converting the catch-cord selvedge waste into yarn, positioning the short tows in unidirectional way is the key issue as the one end of the tows is hold with stitching threads in the off-cut selvedge. So, one of the preferred embodiments referring to Figure 2 of the invention is further trimming the binding threads or re-forming the selvedge edge for positioning the tows and thus any suitable carrier can be added along the stitch line during the re-forming.

[0027] As more spaces between the tows are required for better orientation of the tows, so, the other preferred embodiment, referring to the Figure 5, is that adding of any elastic /expandable materials or threads along the selvedge as catch -cord that will be extended during stretching of the selvedge trim to create more space between the tows for better alignment.

[0028] One of the other preferred embodiment is that using of hot air, micro wave or any thermal system for softening the binding threads / catch-cord of the selvedge edge during stretching and spinning.

[0029] In other embodiment, any air control channel, guide or air suctioning system can be used during the trimming or re-forming of the selvedge trims to hold the tows in one direction for making yarn.

[00301 In one embodiment, the alignment of the tows and yarn formation can be done at the same time or separately. The position of the edges of the short tows or overlapping of the tows can be controlled during the yarn formation process.

[00311 Preferably, said spinning operations are carried out using the wrap spinning or hollow spindle technique referring to the Figure 6 and 7, wherein the catch-cord is pulled out through a spinning device and extra wrapping thread or tape is used to wrap the aligned tows. The wrapping thread may comprise any suitable polymer filaments, ribbons or adhesive material such as polypropylene, polyester, polyamide etc. In certain embodiments of the invention, the number of wraps or turns in the yarn is from 10 to 300 per meter.

[0032] Said catch-cord fabric selvedge comprise carbon fibres tows of length 5 to 200 mm, which may be either pitch based or polyacrylonitrile (PAN) based carbon fibres.

[0033] One of the preferred embodiments of the invention, the composite yarn -and, therefore, the selvedge edge of woven fabric -additionally comprises polymeric filaments/tape as a sheath material referring to the Figure 7.

[0034] In one embodiment, the catch-cord selvedge can be passed through the spinning device directly as it comes from the loom to convert into yarn structure without having any re-forming of the selvedge edge or tows.

[0035] Typically, the yarn according to the first aspect of the present invention, produced in accordance with the method of the second aspect of the invention, has a linear density/mass per unit length in the region of from 0.5 gm/meter to 50 gm/meter.

[0036] According the present invention, continuous yarn made from the selvedge edge can contain carbon fibres from 50-95% by weight.

[0037] After a yarn structure is made in accordance with present discloser, the yarn can be passed through a resin bath for making a composite structures or can be used in fabric for better mechanical properties in the composite as the filament tows are not disintegrated during the process.

[0038] In one embodiment, the woven selvedge waste or catch-cord selvedge can be passed through a resin bath to be used in composite without converting into a yarn form. As an example in pultrusion method, the catch-cord selvedge can be used directly to make composite rod.

[0039] In accordance with present discloser, the waste fabric selvedge of other fibres such as glass, ceramic, steel, kevlar etc can be used into composite structures.

Claims

CLAIMS1. A composite yarn comprising catch-cord selvedge of woven fabric of carbon fibre tows, which comprise short carbon fibres tows.
2. A composite yarn as claimed in claim I wherein said short carbon fibre tows have a length of from 5 to 200 mm.
3. A composite yarn as claimed in claim I or 2 wherein the composite yarn is obtained from waste woven fabric selvedge without breaking or separating the tows.
4. A composite yarn as claimed in claim 1, 2 or 3 which additionally comprises at least one polymeric fibre.
5. A composite yarn as claimed in claim I to 4 wherein the amount of carbon fibres in said composite yarn is typically from 50-95% by weight.
6. A method for the production of a composite yarn from fabric selvedge of carbon fibre material, said method comprising the steps of: (a) providing a catch-cord fabric selvedge comprising short carbon filament tows.(b) re-forming the off cut selvedge for positioning the tows in one direction to convert said materials into yarn; and (c) condensing and spinning the aligned tows so as to form a continuous yarn.
7. A method as claimed in claim 6 wherein said the catch-cord fabric selvedge of carbon fabric to convert into yarn structure without breaking any filaments or disintegrating the tow.
8. A method as claimed in claim 7 wherein said using catch-cord selvedge to convert into yarn comprises re-forming techniques such as trimming or adding suitable carriers or binder prior to processing without breaking the filaments of the tows
9. A method as claimed in claim 8 wherein said using of off cut fabric selvedge to convert into yarn comprises any expandable stitching thread, flexible polymer filament, binder or tape, any natural fibre prior to processing without breaking the filaments of the tows.
10. A method as claimed in claim 9 wherein said the catch-cord selvedge of woven fabric comprises any suitable format prior to processing without disintegrating /breaking the tows.
11. A method as claimed in claim 10 wherein said the catch-cord selvedge of fabric to convert into yarn comprises re-forming at weaving stage or post weaving stage.
12. A method as claimed in any one of claims 1 to II wherein said short carbon filament tows have a length of from 5 to 200 mm.
13. A method as claimed in any one of claims I to 12 wherein said short carbon filament tows fully aligned or partly aligned.
14. A method as claimed in any one of claims 5 to 13 wherein said spinning comprises techniques selected from hollow spindle spinning, wrap spinning and thermal bonding.
15. A method as claimed in claims ito 14 wherein said the catch-cord fabric selvedge to convert into yarn comprises wrap spinning and the wrapping thread comprises polymer filaments, ribbons or adhesive material.
16. A method of using fabric selvedge into yarn as claimed in claims 1 to 15 wherein said comprises sheath materials or additional continuous filaments around the tows.
17. A method of using selvedge into yarn as claimed in claims 1 to 16 wherein said comprises thermal bonding of the tows using any suitable materials.
18. A method of using selvedge into a yarn as claimed in any previous claims wherein said, the linear density / mass (weight) per unit length of the yarn is from 1 gm/meter to 50 gm/meter.
19. A composite yarn as hereinbefore described and with reference to the accompanying description and drawings.
20. A method for the production of a composite yarn as hereinbefore described and with reference tothe accompanying description and drawings21. A composite yarn whenever produced by the method of any one of claims 5 to 20.22. Conversion of selvedge edge into yarn as claimed in any previous claims wherein said the catch-cord selvedge of woven fabric from any reinforcing fibres including glass, ceramic, basalt, steel, Kevlar, inorganic, synthetic inorganic and natural fibres.23. In any claims of claims I to 22 wherein said the composite yarn from catch-cord fabric selvedge comprises any reinforcing fibres to be used into composite applications.24. In any claims of claims I to 23 wherein said the catch-cord selvedge of any reinforcing fibres such as carbon, glass, ceramic, basalt, steel, kevlar including synthetic, inorganic, synthetic inorganic and natural fibres to be used into composite applications either in yarn form or without yarn formation.